I have just completed a $500 transfer to my paypal and am shopping for a new amp, I would like to order it by the end of the week. Problem is I don't have a clue when it comes to amps.

All that I care about here is that I can hear an improvement over my e7/e9 and that I can connect it to my laptop via usb (so it has to have a dac?) I've been pointed to the yulong d100 which looks very promising but I need second opinions because I don't know what to look for.

I would also like to look into some of the shiit tube amps, but that would mean I would need to buy a separate dac?

Any suggestions to help ensure that my $500 is well spent are very appreciated. I can go above my $500 budget but I'd have to wait another few days to transfer more money and I'd rather try and restrain myself here.

IMO moving from the Fiio to the D100 will yield some improvements but it's still an op-amp based amp/DAC which means like all the others it's built around a $5 chip. This same improvement can be had from the likes of the $100 Zero DAC/amp, no need to spend a lot for a little improvement in SQ. The step up would be a discrete DAC and solid-state amp or possibly tube depending on the sound you're looking for.

Where should I be focusing my money if I go down this route? Also I'm not looking for a particular sound, just better sound quality and less background static. I would like whatever I go with to work well with the headphones in my sig.

Ultimately the bump in sound quality will come from a good DAC, given that your phones are sufficiently amped a change in amps will give you a different tone/signature.

The new Schiit Bitfrost (which I have not heard) is likely the cheapest discrete DAC available at $349 new, although I have no idea how this sounds but you should look into that as a standalone DAC option.

I'm not sure what amp to suggest within your price range for your three phones; the AKGs benefit from tubes, apparently the Lyr, or is it the Valhalla is a favorite among owners of that particular combo. The Pro900 can also benefit from a tube to control those piercing highs and give some body to the overly metallic sound. The HD650 however needs something brighter IMO.

Going with separates you will get a better sound but like I say it's hard to suggest a particular one; the D100 will be better than the Fiio but then I would argue so too would the cheaper Zero...

Well if you fancy tube rolling the lyr isn't the best choice, a Woo Audio or Darkvoice might be the better way to go. Different tubes, different sound, better matching to your particular headphones.

For a DAC; the Schiit Bitfrost is cheapest at $350 (but I haven't heard it), the PS Audio DLIII is excellent for the used price of around $500, and the Wyred 4 Sound DAC at $1,000 is also quite popular.

The PS Audio DLIII looks fantastic and is affordable. However the tubes you've just mentioned over the lyr are certainly up there in price... What if I was to go with the DLIII and a solid state? Could I get a good solid state amp for around $400 instead of the $800 - $3000 tubes?

I haven't heard many around that price that are worth recommending. You have your typical D100 (as you mentioned above), a few Meier offerings but in my opinion they don't differ much from the cheap Zero DAC/amp which is priced at $100 used.

A good solid state for under $400... PS Audio GCHA (used, was $995RRP) would be my first choice especially when pairing with the DLIII, it will power just about anything you throw at it. Lehmann Black Cube Linear is also a sweet amp but might be closer to $500-$550, and it gets more expensive from here. M3 self builds are quite popular and should power a good amount of phones but there is no saying how they sound until you hear them.

I think you should define "improvement" to yourself before getting out the wallet.

Most audiophile amps and DACs, including most more expensive ones, are less accurate than the FiiO E7 and E9. Those aren't perfect, but for most headphones, it's hard to find something significantly more accurate since they're pretty close already. Their goal is (relatively) high fidelity. As a mostly true generalization, tube amplifiers and most amplifiers based on certain archaic designs and topologies will degrade (or enhance, depending on your perspective) the contents of your music. The point is that they're intentionally changing things. Is that an improvement to you?

edit: some will be more accurate than the FiiO products, that's for sure. But by a margin that you would consider a big difference (or even one that can be perceived at all)? Probably not.

I think you should define "improvement" to yourself before getting out the wallet.

Most audiophile amps and DACs, including most more expensive ones, are less accurate than the FiiO E7 and E9. Those aren't perfect, but for most headphones, it's hard to find something significantly more accurate since they're pretty close already. Their goal is (relatively) high fidelity. As a mostly true generalization, tube amplifiers and most amplifiers based on certain archaic designs and topologies will degrade (or enhance, depending on your perspective) the contents of your music. The point is that they're intentionally changing things. Is that an improvement to you?

edit: some will be more accurate than the FiiO products, that's for sure. But by a margin that you would consider a big difference (or even one that can be perceived at all)? Probably not.

Where are you getting your information from? You sound like you've been guzzling sales propaganda.

Do you realize that most solid state amps use the same topologies as "archaic" tube amps? They use different components and use a lot of regulation, feedback and other tricks, but the basic amp circuit hasn't changed a whole lot.

You aren't going to argue that old necessarily means bad, are you? I promise there's 1890's technology in your amp. If it works, use it.

The beauty of tubes is that they can be minimalist designs. They don't need a ton of feedback and regulation to be linear. Though not always true, it is generally better to pass the signal through as few components as possible. You have to use quality parts and a well-designed circuit, though.

The reason tubes (done well) cost more is because of power supplies, and especially, output transformers. To deal with high voltage, obtain nicely-filtered DC (this is important) and get output transformers that don't sound awful, you need to go $500-$600 into raw parts. That doesn't consider the rest of the parts or labor. Further, there's more casework and labor for tube amps. It all adds up.

You get paid off in sound and ease of repair. A properly built tube amp can be fixed with almost no fuss. Cheap PCBs can become unrepairable. Even worse, it's nearly impossible to find replacement chips as soon as production ends.

There's a good reason why tubes are used, sought after and hold value.

As for a recommendation, I'd skip the cheap wonderboxes that do everything.

Instead, pick up the new Dynalo for $300. I built one a few years back and they're wonderful. A Dr. Gilmore design, no caps in the signal path, 1W of power, and probably a few thousand have been built by DIY'ers over the years. That's significant, because if the circuit had shortcomings, DIY'ers would have pointed them out and the design would be revised years ago. Also consider how many come up in the For Sale Forum. There are a lot of them out there (also built as the Gilmore Lite) but they don't come up for sale that often. There's a good reason for that.

Sorry if that was unclear. I was lumping in "amps with archaic topologies" (which include many amps which use tubes and many which do not) in with tube amps into the category of "probably not designing it to be as accurate as possible." It seems to me like there's little motivation aside from marketing to use vacuum tubes in headphone amplifier circuits these days, unless you intentionally want distortion.

I'm not arguing that old is necessarily bad at all. A lot of old designs work plenty well for many applications and should still be used.

Of course you can make something good out of about anything, with the right design. I'm sure there are tube amps out there that are very accurate and that have low output impedance if they use an output transformer or have the tube in a certain other part of the circuit.

Out of curiosity, since I'm admittedly not well versed in all the products available, which tube amps have been demonstrated to be extremely accurate? (low output impedance, very low noise, lower than 0.01% THD+N into any headphones at moderate to high volumes, lower than 0.01% IMD, and so on) Any informative links?

Do you have any papers to back up "They [vacuum tubes] don't need a ton of feedback and regulation to be linear"? How linear are you talking about? Sorry for asking for links or proof--it's not that I disbelieve, but that I'm interested in reading if the information is publicly available. Surely it is if some of the popular tube amps perform so well?